This application is based on patent applications No. H10-44243 and H10-362085 filed in Japan, the contents of which are hereby incorporated by reference.
1. Field of the Invention
This invention relates to an image forming apparatus, and more particularly relates to an image forming apparatus which registers a plurality of print jobs in memory, reads out the registered print jobs to print on recording sheets.
2. Description of the Related Art
Heretofore, two types of copying apparatus have been known. One is a type of copying apparatus which prints documents set on platen glass and the other is a type of copying apparatus which executes reading of documents and printing separately and can operate printing of a document read previously during reading of the following document.
The latter type of copying apparatus can read the next document during printing of a document read previously. The image data of the next document is stored in memory as a print-waiting print job, and upon completion of printing of the preceding document, the print-waiting print job is read out from the memory and printed.
Therefore, the operator can start copying of the next document without waiting for completion of printing even though the copying apparatus is currently printing the preceding document.
Such a function is called a multi print job function.
On the other hand, a copying apparatus is usually provided with a plurality of recording sheet trays. The recording sheet trays are classified into two types: the first type of recording sheet tray which accommodates recording sheets of a predetermined standard size (A4, B4, etc.) and cannot accommodate recording sheets of other sizes, and the second type of recording sheet tray which can accommodate recording sheets of various sizes.
Recording sheet trays of the second type are of two types: one is universal recording sheet trays which can accommodate many recording sheets and the other one is hand feed recording sheet trays which cannot accommodate so much recording sheets as the former but can easily gain access from the outside for setting recording sheets.
Because the size of a recording sheet to be accommodated can be changed relatively easily in the case of the second type recording sheet trays, recording sheets of various sizes ranging from the standard sizes such as A4, B4, and etc. to non-standard various sizes are used. In particular, because a recording sheet can be set easily in the case of a hand feed recording sheet tray, various types of recording sheets of not only various recording sheet sizes but also recycled recording sheets, color recording sheets, and OHP recording sheets are used.
When a first type recording sheet tray, for which the recording sheet size is not changed easily, holds no desired recording sheet, the operator sets desired recording sheets on a hand feed recording sheet tray or on a universal recording sheet tray, if the quantity is much, and selects the hand feed recording tray or universal recording sheet tray from an operation panel.
When a recording sheets are fed from a hand feed recording sheet tray or a universal recording sheet tray for copying operation using a copying apparatus having the above-mentioned multi print job, the following problem is caused. That is,
An operator has set desired recording sheets on a hand feed recording tray, selected the hand feed recording sheet tray, performed document reading, and left from the place without confirming that printing is executed as desired.
After that and before the printing is executed, another operator sets new recording sheets with replacing for the previously set recording sheets and operates copying, then as the result, the documents of the former operator are printed on the recording sheets which are set by the latter operator.
Such a trouble is caused particularly in the case of a hand feed recording sheet tray and a universal recording sheet tray. However, such a trouble can be caused also in the case of first type recording sheet trays described herein above. The trouble is caused not only for copying apparatus but also for other various image forming apparatus such as printers which are connected to plural computers.